1. Field of the Invention
The present invention generally relates to a positive photosensitive composition having photosensitivity in the infrared wavelength range, and more particularly to a positive photosensitive composition that is suitable for lithographic photoresists or printing material for what is referred to as direct plateable positive lithography, which allows plates to be directly produced using an infrared laser based on digital signals from a computer or the like.
2. Description of the Related Art
Laser development has been quite remarkable recently. Solid-state lasers and semiconductor lasers in particular, which emit infrared rays having a wavelength ranging from 760 to 1200 nm (hereinafter referred to as xe2x80x9cinfrared lasersxe2x80x9d), are now readily available in the form of small-scale models with high output. Such infrared lasers are extremely useful as printing light sources during the direct production of printing plates based on digital data from computers and the like. There has thus been increasing demand recently for materials that can be used as image recording materials, particularly heat mode laser image recording materials, with high sensitivity for such infrared printing light sources.
Typical examples of positive image recording materials for heat mode lasers include printing materials featuring the use of quinone diazides or diazonium salts such as those disclosed in Japanese Patent Application Laid-Open (JP-A) No.7-285275. Such positive image recording materials utilize dissolution inhibiting effects brought about by the interaction between quinone diazides or diazonium salts, infrared absorbents, and alkaline water-soluble polymers. The quinone diazides or diazonium salts are decomposed upon exposure to laser light, breaking down this interaction, and the parts that are exposed to light are dissolved in alkaline water during development to form positive images. The desired dissolution of the quinone diazides or diazonium salts referred to here means dissolution whereby acid is produced upon reaction with moisture in the system. The acid that is produced facilitates development.
Heat mode exposure systems do not have as much system moisture as UV exposure systems, however, and are thus incapable of producing enough acid from quinone diazides or diazonium salts. One problem, for example, is that the interaction between the infrared absorbent and alkaline water-soluble polymer is restored when allowed to stand for several hours after light exposure, resulting in lower sensitivity and incapacitated development.
As noted above, it has not been possible in the past to obtain a positive photosensitive composition with high sensitivity to heat mode lasers, good development latitude, and good storage stability.
An object of the present invention is to provide a positive photosensitive composition with high sensitivity to heat mode lasers, good development latitude, and good storage stability.
As a result of extensive research, the inventors perfected the present invention upon finding that the aforementioned drawbacks can be resolved by the following means.
Specifically, the positive photosensitive composition of the present invention comprises at least a diazo compound represented by the following General Formula 1, and a water-insoluble but alkaline water-soluble polymer: 
(where Z represents an organic group in which the pKa of dissociating H in Phxe2x80x94NHxe2x80x94Z is 14 or less; and Q1 and Q2 represent organic groups, where Q1 and Q2 may be bonded to form an aliphatic ring or aromatic ring).
The organic group z referred to here is preferably xe2x80x94SO2R1 or xe2x80x94COR2 (where R1 represents a hydrocarbon group, and R2 represents a hydrocarbon group with an electron-attracting substituent), and the hydrocarbon group R2 preferably has any electron-attractive substituent selected from the group consisting of halogen atoms, substituted sulfonyl groups, nitro groups, cyano groups, alkoxy groups, and hydroxy groups.
The positive photosensitive composition of the present invention also preferably further comprises an infrared absorbent.
It is assumed that the development properties during exposure are not improved very much in conventional positive image recording materials for heat mode lasers because the quinone diazides or diazonium salts contained in the material produce intermediates that are highly reactive during exposure-induced decomposition, and that the intermediates become insoluble upon reaction with the alkaline water-soluble polymer serving as the binder.
For example, the naphthoquinone diazide used in positive image recording materials with UV exposure produce highly reactive ketenes when decomposed upon exposure. In UV light systems, the ketenes react with moisture in the material and are inactivated in the form of carboxylic acids, but it is assumed that the elevated heat in heat mode systems results in less moisture in the material and prevents the ketenes from reacting with water molecules, and that these ketenes react with the alkaline water-soluble polymer, rendering the alkaline water-soluble polymer insoluble.
A feature of the positive photosensitive composition of the present invention is the use of a diazo compound represented by the aforementioned General Formula 1 as an acid-producing agent. Because of its inherent structure, the diazo compound is believed to selectively react with water molecules to facilitate development during exposure, without producing ketenes that are highly reactive with alkaline water-soluble polymers when decomposed upon exposure.
The positive photosensitive composition of the present invention is described in detail below.
(A) Diazo Compounds Represented by General Formula 1
The diazo compounds of the present invention are characterized by being represented by the following General Formula 1. 
In General Formula 1, Z represents an organic group selected so that the pKa of the dissociating hydrogen in compound Phxe2x80x94NHxe2x80x94Z, where the amino group of Phxe2x80x94NH2 is substituted by Z, is 14 or less. The organic group Z is not particularly limited, provided that it meets these conditions, although xe2x80x94SO2R1 and xe2x80x94COR2 (where R1 represents a hydrocarbon group, and R2 represents a hydrocarbon group with an electron-attracting substituent) are particularly preferred.
The hydrocarbon group R1 of the organic group xe2x80x94SO2R1 may have a substituent, and may include an unsaturated bond. Examples of such hydrocarbon groups include alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, alkenyl groups, substituted alkenyl groups, alkinyl groups, and substituted alkinyl groups.
Examples of alkyl groups include C1 to C20 linear, branched, or cyclic alkyl groups, specific examples of which include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl groups. Of these, C1 to C12 linear alkyls, C3 to C12 branched alkyls, and C5 to C10 cyclic alkyls are preferred.
Substituted alkyl groups are composed by a bond between the substituent and alkylene group. Monovalent nonmetallic atom groups except for hydrogen are used as substituents. Preferred examples include halogen atoms (xe2x80x94F, xe2x80x94Br, xe2x80x94Cl, xe2x80x94I), hydroxy groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, N-alkylamino groups, N,N-dialkylamino groups, N-arylamino groups, N,N-diarylamino groups, N-alkyl-N-arylamino groups, acyloxy groups, carbamoyloxy groups, N-alkylcarbamoyloxy groups, N-arylcarbamoyloxy groups, N,N-dialkylcarbamoyloxy groups, N,N-diarylcarbamoyloxy groups, N-alkyl-N-arylcarbamoyloxy groups, alkylsulfoxy groups, arylsulfoxy groups, acylthio groups, acylamino groups, N-alkylacylamino groups, N-arylacylamino groups, ureido groups, Nxe2x80x2-alkylureido groups, Nxe2x80x2,Nxe2x80x2-dialkylureido groups, Nxe2x80x2-arylureido groups, Nxe2x80x2,Nxe2x80x2-diarylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-arylureido groups, N-alkylureido groups, N-arylureido groups, Nxe2x80x2-alkyl-N-alkylureido groups, Nxe2x80x2-alkyl-N-arylureido groups, Nxe2x80x2,Nxe2x80x2-dialkyl-N-alkylureido groups, Nxe2x80x2,Nxe2x80x2-dialkyl-N-arylureido groups, Nxe2x80x2-aryl-N-alkylureido groups, Nxe2x80x2-aryl-N-arylureido groups, Nxe2x80x2,Nxe2x80x2-diaryl-N-alkylureido groups, Nxe2x80x2,Nxe2x80x2-diaryl-N-arylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-aryl-N-alkylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-aryl-N-arylureido groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, N-alkyl-N-alkoxycarbonylamino groups, N-alkyl-N-aryloxycarbonylamino groups, N-aryl-N-alkoxycarbonylamino groups, N-aryl-N-aryloxycarbonylamino groups, formyl groups, acyl groups, carboxy groups and their conjugate base groups (hereinafter referred to as carboxylates), alkoxycarbonyl groups, aryloxycarbonyl groups, carbamoyl groups, N-alkylcarbamoyl groups, N,N-dialkylcarbamoyl groups, N-arylcarbamoyl groups, N,N-diarylcarbamoyl groups, N-alkyl-N-arylcarbamoyl groups, alkylsulfinyl groups, arylsulfinyl groups alkylsulfonyl groups, arylsulfonyl groups, sulfo groups (xe2x80x94SO3H) and their conjugate base groups (hereinafter referred to as sulfonate groups), alkoxysulfonyl groups, aryloxysulfonyl groups, sulfinamoyl groups, N-alkylsulfinamoyl groups, N,N-dialkylsulfamoyl groups, N-arylsulfamoyl groups, N,N-diarylsulfinamoyl groups, N-alkyl-N-arylsulfinamoyl groups, sulfamoyl groups, Nalkylsulfamoyl groups, N,N-dialkylsulfainoyl groups, N-arylsulfamoyl groups, N,N-diarylsulfamoyl groups, N-alkyl-N-arylsulfamoyl groups, N-acylsulfamoyl groups and their conjugate base groups, N-alkylsulfonylsulfamoyl groups (xe2x80x94SO2NHSO2 (aryl)) and their conjugate base groups, N-ar ylsulfonylsulfamoyl groups (xe2x80x94SO2NHSO2 (allyl)) and their conjugate base groups, N-alkylsulfonylcarbamoyl groups (xe2x80x94CONHSO2 (alkyl)) and their conjugate base groups, N-arylsulfonylcarbamoyl groups (xe2x80x94CONHSO2 (aryl)) and their conjugate base groups, alkoxysilyl groups (xe2x80x94Si(Oalkyl)3), aryloxysilyl groups (xe2x80x94Si(Oaryl)3), hydroxysilyl groups (xe2x80x94Si(OH)3) and their conjugate base groups, phosphono groups (xe2x80x94PO3H2) and their conjugate base groups (hereinafter referred to as phosphonato groups), dialkylphosphono groups (xe2x80x94PO3 (alkyl)2), diarylphosphono groups (xe2x80x94PO3 (aryl)2), alkylallylphosphono groups (xe2x80x94PO3 (alkyl) (aryl), monoalkylphosphono groups (xe2x80x94PO3H (alkyl)) and their conjugate base groups (hereinafter referred to as alkylphosphonato groups), monoallylphosphono groups (xe2x80x94PO3H (aryl)) and their conjugate base groups (hereinafter referred to as allylphosphonato groups), phosphonoxy groups (xe2x80x94OPO3H2) and their conjugate base groups (hereinafter referred to as phosphonatoxy groups), dialkylphosphonoxy groups (xe2x80x94OPO3(alkyl)2), diallylphosphonoxy groups (xe2x80x94OPO3(aryl)2), alkylallylphosphonoxy groups (xe2x80x94OPO3(alkyl) (aryl), monoalkylphosphonoxy groups (xe2x80x94OPO3H(alkyl) and their conjugate base groups (hereinafter referred to as alkylphosphonatoxy groups), monoarylphosphonoxy groups (xe2x80x94OPO3H(aryl) and their conjugate base groups (hereinafter referred to as allylphosphonatoxy groups), cyano groups, nitro groups, aryl groups, alkenyl groups, and alkynyl groups.
Specific examples of alkyl groups in these substituents include the aforementioned alkyl groups. Specific examples of aryl groups include phenyl, biphenyl, naphthyl, tolyl, xylyl, mesityl, cumenyl, fluorophenyl, chlorophenyl, bromophenyl, chloromethylphenyl, hydroxyphenyl, methoxyphenyl, ethoxyphenyl, phenoxyphenyl, acetoxyphenyl, benzoyloxyphenyl, methylthiophenyl, phenylthiophenyl, methylaminophenyl, dimethylaminophenyl, acetylaminophenyl, carboxyphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl, phenoxycarbonylphenyl, N-phenylcarbamoylphenyl, phenyl, nitrophenyl, cyanophenyl, sulfophenyl, sulfonatophenyl, phosphonophenyl, and phosphonatophenyl groups. Examples of alkenyl groups include vinyl, 1-propenyl, 1-butenyl, cinnamyl, and 2-chloro-1-ethenyl groups. Examples of alkinyl groups include ethinyl, 1-propinyl, 1-butinyl, trimethylsilylethinyl, and phenylethinyl groups.
Of the aforementioned substituents, electron attractive substituents such as halogen atoms, nitro groups, and substituted carbonyl groups are preferred.
Examples of aryl groups include those forming condensed rings with 1 to 3 benzene rings, and those forming condensed rings with benzene rings and 5-membered unsaturated rings. Specific examples include phenyl, naphthyl, anthryl, phenanthryl, indenyl, acenaphthenyl, and fluorenyl groups. Of these, phenyl and naphthyl are preferred.
Substituted aryl groups used in the invention have the substituent bonded to the aryl group, and have a monovalent nonmetallic atomic group except for hydrogen as the substituent on the ring-forming carbon atom of the aforementioned aryl group. Examples of desirable substituents include the aforementioned alkyl groups, substituted alkyl groups, and those given earlier as examples of substituents for substituted alkyl groups. Specific examples of desirable substituted aryl groups include biphenyl, tolyl, xylyl, mesityl, cumenyl, chlorophenyl, bromophenyl, fluorophenyl, chloromethylphenyl, trifluoromethylphenyl, hydroxyphenyl, methoxyphenyl, methoxyethoxyphenyl, allyloxyphenyl, phenoxyphenyl, methylthiophenyl, tolylthiophenyl, phenylthiophenyl, ethylaminophenyl, diethylaminophenyl, morpholinophenyl, acetyloxyphenyl, benzoyloxyphenyl, N-cyclohexylcarbamoyloxyphenyl, N-phenylcarbamoyloxyphenyl, acetylaminophenyl, N-methylbenzoylaminophenyl, carboxyphenyl, methoxycarbonylphenyl, allyloxycarbonylphenyl, chlorophenoxycarbonylphenyl, carbamoylphenyl, N-methylcarbamoylphenyl, N,N-dipropylcarbamoylphenyl, N-(methoxyphenyl)carbamoylphenyl, N-methyl-N-(sulfophenyl)carbamoylphenyl, sulfophenyl, sulfonatophenyl, sulfamoylphenyl, N-ethylsulfamoylphenyl, N,N-dipropylsulfamoylphenyl, N-tolylsulfamoylphenyl, N-methyl-N-(phosphonophenyl)sulfamoylphenyl, phosphonophenyl, phosphonatophenyl, diethylphosphonophenyl, diphenylphosphonophenyl, methylphosphonophenyl, methylphosphonatophenyl, tolylphosphonophenyl, tolylphosphonatophenyl, allyl, 1-propenylmethyl, 2-butenyl, 2-methylallylphenyl, 2-methylpropenylphenyl, 2-propinylphenyl, 2-butinylphenyl, and 3-butinylphenyl.
Examples of alkenyl groups include vinyl, 1-propenyl, 1-butenyl, cinnamyl, and 2-chloro-1-ethenyl groups. In substituted alkenyl groups, the substituent replaces the hydrogen atom of the alkenyl groups. Examples of such substituents include the substituents in the aforementioned substituted alkyl groups.
The following are examples of preferred substituted alkenyl groups. 
Examples of alkinyl groups include ethinyl, 1-propinyl, 1-butinyl, trimethylsilylethinyl, and phenylethinyl groups. In substituted alkinyl groups, the substituent is bonded instead of the hydrogen atom of the alkinyl groups. Examples of such substituents include the substituents in the aforementioned substituted alkyl groups.
The hydrocarbon R2 having an electron attracting substituent group in the organic group xe2x80x94COR2 may have a substituent, and may include an unsaturated bond. Examples of hydrocarbon groups include the same alkyl groups, allyl groups, alkenyl groups, and alkinyl groups as for the hydrocarbon group R1. Those having a halogen atom, substituted sulfonyl group, nitro group, cyano group, alkoxy group, or hydroxy group as the electron attracting substituent are preferred.
Q1 and Q2 in General Formula represent organic groups. Q1 and Q2 may be the same as or different from each other. Q1 and Q2 may also be bonded together to form a ring.
Examples of organic groups Q1 and Q2 include hydrocarbon groups, heterocyclic groups, substituted oxy groups, substituted thio groups, substituted amino groups, substituted carbonyl groups, substituted sulfinyl groups, substituted sulfonyl groups, substituted phosphono groups, substituted phosphonato groups, substituted phosphoryl groups, and cyano groups.
The hydrocarbon groups represented by Q1 and Q2 may have substituents and may include unsaturated bonds. Examples of hydrocarbon groups represented by Q1 and Q2 include the same alkyl groups, substituted alkyl groups, allyl groups, substituted allyl groups, alkenyl groups, substituted alkenyl groups, alkinyl groups, and substituted alkinyl groups as for the hydrocarbon group R1.
Heterocyclic groups are monovalent groups with one hydrogen on the hetero ring removed, and monovalent groups (substituted heterocyclic groups) with another hydrogen removed from the above monovalent group, having substituents from among the aforementioned substituted alkyl groups bonded thereto.
The following heterocyclic groups are preferred as the hetero ring represented by Q1 and Q2. 
Examples of substituted oxy groups (R5Oxe2x80x94) represented by Q1 and Q2 which can be used include those in which R1 is a monovalent nonmetallic atomic group except for hydrogen. Examples of desirable substituted oxy groups include alkoxy, aryloxy, acyloxy, carbamoyloxy, N-alkylcarbamoyloxy, N-arylcarbamoyloxy, N, N-dialkylcarbamoyloxy, N, N-diarylcarbamoyloxy, N-alkyl-N-arylcarbamoyloxy, alkylsulfoxy, arylsulfoxy, phosphonoxy, and phosphonatoxy groups. Examples of alkyl and allyl groups for these include the aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups. Examples of acyl groups (R6COxe2x80x94) for acyloxy groups include those in which R6 is an aforementioned alkyl, substituted alkyl, aryl, or substituted aryl group. Alkoxy groups, aryloxy groups, acyloxy groups, and arylsulfoxy groups are preferred among such substituents. Specific examples of preferred substituted oxy groups include methoxy, ethoxy, propyloxy, isopropyloxy, butyloxy, pentyloxy, hexyloxy, dodecyloxy, benzyloxy, allyloxy, phenethyloxy, carboxyethyloxy, methoxycarbonylethyloxy, ethoxycarbonylethyloxy, methoxyethoxy, phenoxyethoxy, methoxyethoxyethoxy, ethoxyethoxyethoxy, morpholinoethoxy, morpholinopropyloxy, allyloxyethoxyethoxy, phenoxy, tolyloxy, xylyloxy, mesityloxy, cumenyloxy, methoxyphenyloxy, ethoxyphenyloxy, chlorophenyloxy, bromophenyloxy, acetyloxy, benzoyloxy, naphthyloxy, phenylsulfonyloxy, phosphonoxy, and phosphonatoxy groups.
Examples of substituted thio groups (R7Sxe2x80x94) represented by Q1 and Q2 include those in which R7 is a monovalent nonmetallic atomic group except for hydrogen. Examples of desirable substituted thio groups include alkythio groups, arylthio groups, alkyldithio groups, aryldithio groups, and acylthio groups. Examples of alkyl and aryl groups for these include the aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups. R6 of the acyl group (R6COxe2x80x94) in acylthio groups are the same as above. Alkylthio and arylthio groups are preferred among these. Specific examples of desirable substituted thio groups include methylthio, ethylthio, phenylthio, ethoxyethylthio, carboxyethylthio, and methoxycarbonylthio groups.
Examples of substituted amino groups (R8NHxe2x80x94, (R9) (R10)Nxe2x80x94) represented by Q1 and Q2 which can be used include those in which R8, R9, and R10 are monovalent nonmetallic atomic groups except for hydrogen. Preferred examples of substituted amino groups include N-alkylamino group, N,N-dialkylamino groups, N-arylamino groups, N,N-diarylamino groups, N-alkyl-N-arylamino groups, acylamino groups, N-alkylacylamino groups, N-arylacylamino groups, ureido groups, Nxe2x80x2-alkylureido groups, Nxe2x80x2,Nxe2x80x2-dialkylureido groups, Nxe2x80x2-arylureido groups, Nxe2x80x2,Nxe2x80x2-diarylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-arylureido groups, N-alkylureido groups, N-arylureido groups, Nxe2x80x2-alkyl-N-alkylureido groups, Nxe2x80x2-alkyl-N-arylureido groups, Nxe2x80x2,Nxe2x80x2-dialkyl-N-alkylureido groups, Nxe2x80x2,Nxe2x80x2-dialkyl-N-arylureido groups, Nxe2x80x2-aryl-N-alkylureido groups, Nxe2x80x2-aryl-N-arylureido groups, Nxe2x80x2,Nxe2x80x2-diaryl-N-alkylureido groups, Nxe2x80x2,Nxe2x80x2-diaryl-N-arylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-aryl-N-alkylureido groups, Nxe2x80x2-alkyl-Nxe2x80x2-aryl-N-arylureido groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, N-alkyl-N-alkoxycarbonylamino groups, N-alkyl-N-aryloxycarbonylamino groups, N-aryl-N-alkoxycarbonylamino groups, and N-aryl-N-aryloxycarbonylamino groups. The aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups can be used as alkyl and aryl groups here. R6 of the acyl group (R6COxe2x80x94) in acylamino groups, N-alkylacylamino groups, and N-arylacylamino groups is the same as above. N-alkylamino groups, N,N-dialkylamino groups, N-arylamino groups, and acylamino groups are preferred among these. Specific examples of desirable substituted amino groups include methylamino, ethylamino, diethylamino, morpholino, piperidino, pyrrolidino, phenylamino, benzoylamino, and acetylamino groups.
Examples of substituted carbonyl groups (R11xe2x80x94COxe2x80x94) represented by Q1 and Q2 include those in which R11 is a monovalent nonmetallic atomic group. Desirable examples of substituted carbonyl groups include formyl, acyl, carboxy, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, N-alkylcarbamoyl, N,N-dialkylcarbamoyl, N-arylcarbamoyl, N,N-diarylcarbamoyl, and N-alkyl-N-arylcarbamoyl groups. The aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups can be used as alkyl and aryl groups here. Examples of more desirable substituents among these include formyl, acyl, carboxy, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, N-arylcarbamoyl, N,N-dialkylcarbamoyl, and N-arylcarbamoyl groups. Even more desirable examples include formyl, acyl, alkoxycarbonyl, and aryloxycarbonyl groups. Specific examples of desirable substituents include formyl, acetyl, benzoyl, carboxy, methoxycarbonyl, allyloxycarbonyl, N-methylcarbamoyl, N-phenylcarbamoyl, N,N-diethylcarbamoyl, and morpholinocarbonyl groups.
Examples of substituted sulfinyl groups (R12xe2x80x94SOxe2x80x94) represented by Q1 and Q2 include those in which R12 is a monovalent nonmetallic atomic group. Desirable examples include alkinylsufinyl, arylsulfinyl, sulfinamoyl, N-alkylsulfinamoyl, N,N-dialkylsulfinamoyl, N-arylsulfinamoyl, N,N-diarylsufinamoyl, and N-alkyl-N-arylsulfinamoyl groups. The aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups can be used as alkyl and aryl groups here. Examples that are preferred among these include alkylsulfinyl and arylsulfinyl groups. Specific examples of such substituted sulfinyl groups include hexylsulfinyl, benzylsulfinyl, and tolylsulfinyl groups.
Examples of substituted sulfonyl groups (R13xe2x80x94OS2xe2x80x94) represented by Q1 and Q2 include those in which R13 is a monovalent nonmetallic atomic group. Preferred examples include alkylsulfonyl and arylsulfonyl groups. The aforementioned alkyl, substituted alkyl, aryl, and substituted aryl groups can be used as alkyl and aryl groups here. Specific examples of such substituted sulfonyl groups include butylsulfonyl and chlorophenylsulfonyl groups.
Substituted phosphono groups mean those in which one or two hydroxyl groups on the phosphono group have been substituted by another organic oxo group. Desirable examples of substituted phosphono groups represented by Q1 and Q2 include the aforementioned dialkylphosphono groups, diarylphosphono groups, alkylarylphosphono groups, monoalkylphosphono, and monoarylphosphono groups. Dialkylphosphono and diarylphosphono groups are preferred among these. Specific examples include diethylphosphono, dibutylphosphono, and diphenylphosphono groups.
Substituted phosphonato groups are conjugate base anion groups of the aforementioned phosphono groups in which one hydroxyl group has been substituted with an organic oxo group. Specific examples include the conjugate base groups of the aforementioned monoalkylphosphono (xe2x80x94PO3H (alkyl)) and monoarylphosphono (xe2x80x94PO3H (aryl)) groups. Ordinarily, they are preferably used with counter cations. Examples of such counter cations include those which are commonly known, such as various oniums (ammonium, sulfonium, phosphonium, iodonium, azinium, and the like) and metal ions (such as Na+, K+, Ca2+, and Zn2+)
Examples of phosphoryl groups represented by Q1 and Q2 include diphenylphosphoryl.
Hydrocarbon groups, substituted carbonyl groups, and substituted phosphoryl groups are preferred as organic groups represented by Q1 and Q2 among the aforementioned substituents. Hydrocarbon groups preferably include hetero atoms.
The organic groups Q1 and Q2 preferably are bonded together to form aliphatic rings or aromatic rings. Aromatic rings such as benzene rings, naphthalene rings, or anthracene rings are preferably formed for the sake of more stable conjugation.
The rings may also have substituents. Examples of substituents include those given as examples of substituents for the aforementioned substituted alkyl groups. Some of the ring constituent carbons may also be substituted by hetero atoms (such as oxygen, sulfur, and nitrogen atoms). Some of the aliphatic rings may also form some of the aromatic rings.
The organic groups Q1 and Q2 may also be substituted by a residue of General Formula 1.
The following are specific examples of diazo compounds represented by General Formula 1.

Such diazo compounds are commonly synthesized as represented in the following schemes. 
(Scheme 3) Bamford-Stevens reaction of corresponding ketone
Scheme 1 is the most commonly used of these.
Details of the aforementioned methods are given in Chapters 14, 15, and 17 in particular in The Chemistry of Functional Groups: The Chemistry of Diazonium and Diazo Groups, Parts 1 and 2, by Saul Patai, John Wiley and Sons (1978).
The diazo compounds of the present invention are particularly suitable for positive lithographic printing materials for heat mode printing in which the plates have a low moisture content during development.
(B) Water-Insoluble and Alkaline Water-Soluble Polymers
A polymer (B) that is water-insoluble but alkaline water-soluble (alkaline water-soluble polymer), that is, a homopolymer with acidic groups in the polymer main chain and/or side chains, a copolymer thereof, or a mixture thereof, is used as the binder polymer in the positive photosensitive composition of the present invention. The positive photosensitive composition of the present invention can thus be developed in an alkaline developer.
Those with acidic groups in the polymer main chain and/or side chains in (1) through (6) below are preferred for the sake of dissolution in alkaline developers and the ability to control such dissolution.
(1) phenol groups (xe2x80x94Arxe2x80x94OH)
(2) sulfonamide groups (xe2x80x94SO2NHxe2x80x94R)
(3) substituted sulfonamide acid groups (hereinafter referred to as xe2x80x9cactive imide groupsxe2x80x9d) (xe2x80x94SO2NHCOR, xe2x80x94SO2NHSO2R, xe2x80x94CONHSO2R)
(4) carboxylic acid groups (xe2x80x94CO2H)
(5) sulfonic acid groups (xe2x80x94SO3H)
(6) phosphoric acid groups (xe2x80x94OPO3H2)
In (1) and (6) above, Ar represents an optionally substituted divalent aryl linkage, and R represents an optionally substituted hydrocarbon group.
Alkaline water-soluble polymers with (1) phenol groups, (2) sulfonamide groups, and (3) active imide groups are preferred among the alkaline water-soluble polymers with acidic groups selected from (1) through (6) above. Alkaline water-soluble polymers having (1) phenol groups or (2) sulfonamide groups are ideal in terms of solubility in alkaline developers, development latitude, and adequately preserved film strength.
The following are examples of alkaline water-soluble polymers with acidic groups selected from (1) through (6) above.
Examples of alkaline water-soluble polymers having (1) phenol groups include condensation polymers of phenol and formaldehyde, condensation polymers of m-cresol and formaldehyde, condensation polymers of p-cresol and formaldehyde, condensation polymers of m-/p-cresol mixtures and formaldehyde, condensation polymers of phenol and cresol (m-, p-, or m-/p-mixtures) and formaldehyde, and similar novolak resins, as well as condensation polymers of pyrogallol and acetone. Alternatively, copolymers comprising the copolymers of compounds having phenol groups in the side chains can also be used.
Examples of compounds with phenol groups include phenol group-containing acrylamides, methacrylamides, acrylate esters, methacrylate esters, and hydroxystyrene.
Specific examples include N-(2-hydroxyphenyl) acrylamide, N-(3-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)acrylamide, N-(2-hydroxyphenyl) methacrylamide, N-(3-hydroxyphenyl)methacrylamide, N-(4-hydroxyphenyl)methacrylamide, o-hydroxyphenylacrylate, m-hydroxyphenylacrylate, p-hydroxyphenylacrylate, o-hydroxyphenylmethacrylate, m-hydroxyphenylmethacrylate, p-hydroxyphenylmethacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2-(2-hydroxyphenyl)ethylacrylate, 2-(3-hydroxyphenyl)ethylacrylate, 2-(4-hydroxyphenyl)ethylacrylate, 2-(2-hydroxyphenyl)ethylmethacrylate, 2-(3-hydroxyphenyl)ethylmethacrylate, and 2-(4-hydroxyphenyl)ethylmethacrylate.
The weight-average molecular weight of the polymer is between 5.0xc3x97102 to 2.0xc3x97104, and a number average molecular weight of 2.0xc3x97102 to 1.0xc3x97104 is preferred for the sake of image formation. These polymers may be used alone or in combinations of two or more. When combined, condensation polymers of t-butylphenol and formaldehyde such as that described in U.S. Pat. No. 4,123,279, and condensation polymers of formaldehyde and phenols with C3 to C8 alkyl groups as substituents, such as condensation polymers of octylphenol and formaldehyde, may also be used.
Examples of alkaline water-soluble polymers having (2) sulfonamide groups include polymers comprising minimum structural units derived from compounds having sulfonamide groups as a primary constituent. Examples of such compounds include compounds having at least one each of a sulfonamide group with at least one hydrogen atom bonded to a nitrogen atom, and a polymerizable unsaturated group, per molecule.
Preferred among these are low molecular weight compounds having an acryloyl group, allyl group, or vinyloxy group and a substituted or mono-substituted aminosulfonyl group or substituted sulfonylimino group per molecule. Examples include the following compounds represented by General Formulas 2 through 6. 
(Where X1 and X2 each independently represent xe2x80x94Oxe2x80x94 or xe2x80x94NR27xe2x80x94. R21 and R24 each independently represent a hydrogen atom or xe2x80x94CH3. R22, R25, R29, R32, and R36 each independently represent an optionally substituted C1 to C12 alkylene group, cycloalkylene group, arylene group, or aralkylene group. R23, R27, and R33 each independently represent a hydrogen atom, an optionally substituent-bearing C1, to C12 alkyl group, cycloalkyl group, aryl group, or aralkyl group. R26 and R37 each independently represent an optionally substituent-bearing C1 to C12 alkyl group, cycloalkyl group, aryl group, or aralkyl group. R28, R30, and R34 each independently represent a hydrogen atom or xe2x80x94CH3. R31 and R35 each independently represent a C1 to C12 alkylene group, cycloalkylene group, arylene group, or aralkylene group which may have a substituent or a single bond. Y5 and Y6 each independently represent a single bond or xe2x80x94COxe2x80x94.)
The use of m-aminosulfonylphenyl methacrylate, N-(p-aminosulfonylphenyl) methacrylamide, N-(p-aminosulfonylphenyl) acrylamide and the like is preferred among the compounds represented by General Formulas 2 through 6 in the positive photosensitive composition of the present invention.
Examples of alkaline water-soluble polymers having (3) active imide groups include polymers comprising minimum structural units derived from compounds having active imide groups as a primary constituent. Examples of such compounds include compounds having at least one each of an active imide group represented by the following structural formula and a polymerizable unsaturated group per molecule. 
Specifically, the use of N-(p-toluenesulfonyl) methacrylamide, N-(p-toluenesulfonyl)acrylamide, and the like is preferred.
Examples of alkaline water-soluble polymers having (4) carboxylic acid groups include polymers comprising as a primary substituent minimum structural units derived from compounds having at least one each of a carboxylic acid group and a polymerizable unsaturated group per molecule.
Examples of alkaline water-soluble polymers having (5) sulfonic acid groups include polymers comprising as a primary substituent minimum structural units derived from compounds having at least one each of a sulfonic acid group and a polymerizable unsaturated group per molecule.
Examples of alkaline water-soluble polymers having (6) phosphoric acid groups include polymers comprising as a primary substituent minimum structural units derived from compounds having at least one each of a phosphoric acid group and a polymerizable unsaturated group per molecule.
Preferred among the aforementioned alkaline water-soluble polymers are alkaline water-soluble polymers having (1) phenolic hydroxyl groups because of the ability to obtain potent hydrogen bonding interaction between specific functional groups xe2x80x94Xxe2x80x94Yxe2x80x94Z of such phenolic compounds.
The minimum structural units having acidic groups selected from (1) through (6) above forming the alkaline water-soluble polymer used in the positive photosensitive composition of the present invention need not necessarily be of only one kind. Those comprising the copolymerization of two or more kinds of minimum structural units with the same acidic groups or two or more kinds of minimum structural units with different acidic groups can be used.
Examples of copolymerization methods which can be used include conventionally known graft copolymerization, block copolymerization, and random copolymerization.
Such copolymers preferably include 10 mol % or more, and more preferably 20 mol % or more, of compounds with acidic groups selected from (1) through (6). Less than 10 mol % usually will not result in satisfactory improvement in development latitude.
When these compounds are copolymerized into copolymers in the present invention, other compounds which do not contain the aforementioned acidic groups in (1) through (6) can also be used. The compounds in (ml) through (ml2) below are examples of other compounds without the acidic groups in (1) through (6).
(m1) Examples include acrylic acid esters and methacrylic acid esters having aliphatic hydroxyl groups, such as 2-hydroxyethylacrylate and 2-hydroxyethylmethacrylate.
(m2) Examples include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, and N-dimethylaminoethyl acrylate.
(m3) Examples include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, and N-dimethylaminoethyl methacrylate.
(m4) Examples include acrylamides and methacrylamides such as acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, and N-ethyl-N-phenyl acrylamide.
(m5) Examples include vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(m6) Examples include vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, and vinyl benzoate.
(m7) Examples include styrenes such as styrene, xcex1-methylstyrene, methylstyrene, and chloromethylstyrene.
(m8) Examples include vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(m9) Examples include olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene.
(m10) Examples include N-vinyl pyrrolidone, N-vinyl carbazole, 4-vinyl pyridine, acrylonitrile, and methacrylonitrile.
(m11) Examples include unsaturated imides such as maleimide, N-acryloyl acrylamide, N-acetyl methacrylamide, N-propionyl methacrylamide, and N-(p-chlorobenzoyl)methacrylamide.
(m12) Examples include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.
The alkaline water-soluble polymer used in the positive photosensitive composition of the present invention, whether a homopolymer or copolymer, should have a weight-average molecular weight of 1.0xc3x97103 to 2.0xc3x97105, and a number average molecular weight of 5.0xc3x97102 to 1.0xc3x97105 for the sake of sensitivity and development latitude. The distribution (weight-average molecular weight/number average molecular weight) is preferably between 1.1 and 10.
When a copolymer is used in the present invention, the blend weight ratio between the minimum structural units derived from compounds having acidic groups selected from (1) through (6) above forming the main chain and/or side chains, and the other minimum structural units without the acidic groups of (1) through (6) forming a part of the main chain and/or side chains, should range between 50:50 and 5:95, and even more preferably between 40:60 and 10:90.
The aforementioned alkaline water-soluble polymers may be used individually or in combinations of two or more. They should be used within a range of between 30 and 99 wt %, preferably between 40 and 95 wt %, and even more preferably between 50 and 90 wt %, of the total solids of the positive photosensitive composition.
When the alkaline water-soluble polymer is used in an amount of less than 30 wt %, the printing layer durability tends to deteriorate, whereas more than 99 wt % tends to result in lower sensitivity and durability.
Novolak resins are described below.
Examples of novolak resins suitable for use in the present invention include condensation polymers of phenol and formaldehyde, condensation polymers of m-cresol and formaldehyde, condensation polymers of p-cresol and formaldehyde, condensation polymers of m-/p-cresol mixtures and formaldehyde, condensation polymers of phenol and cresol (m-, p-, or m-/p-mixtures) and formaldehyde, and similar novolak resins, as well as condensation polymers of pyrogallol and acetone. Alternatively, copolymers of monomers having phenol groups in the side chains can also be used.
Examples of solvents which can be used during the synthesis of the alkaline water-soluble polymers used in the present invention include tetrahydrofuran, ethylene dichloride, cyclohexane, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, N,N-dimethyl formamide, N,N-dimethyl acetamide, toluene, ethyl acetate, methyl acetate, ethyl lactate, dimethyl sulfoxide, and water. These solvents may be used alone or in combinations of two or more.
(C) Infrared Absorbents
Various pigments or dyes can be used as infrared absorbents in the present invention.
Examples of pigments include commercially available pigments and pigments listed in the Color Index (C.I.) Manual, Saishin Ganryo Binran [Recent Pigments Manual] (ed. by Nihon Ganryo Gijutsu Kyokai (1977)), Saishin Ganryo Oyo Gijutsu [Recent Pigment Applications and Techniques] (published by CMC (1986 ed.)), and Insatsu Inki Gijutsu [Printing Ink Techniques] (published by CMC (1984)).
Types of pigments include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, violet pigments, blue pigments, green pigments, fluorescent pigments, metallic powder pigments, and other polymer bonded dyes. Specific examples which can be used include insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, printing lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, and carbon black.
These pigments can be used with or without surface treatment. Methods of surface treatment include methods for coating surfaces with resin or wax, methods for applying surfactants, and methods for allowing reactive substances (such as silane coupling agents, epoxy compounds, and polyisocyanates) to bond to the surface of the pigments. The aforementioned surface treatments are described in Kinzoku Sekken no Seishitsu to Oyo [Metal Soap Properties and Applications] (published by Koshobo), Insatsu Inki Gijutsu [Printing Ink Techniques] (published by CMC (1984)), and Saishin Ganryo Oyo Gijutsu [Recent Pigment Applications and Techniques] (published by CMC (1986 ed.)).
The pigment particle diameter preferably ranges between 0.01 and 10 xcexcm, more preferably between 0.05 and 1 xcexcm, and even more preferably between 0.1 and 1 xcexcm. A pigment particle diameter of less than 0.01 xcexcm is undesirable in terms of the stability of the dispersed material in the photosensitive layer coating solution, while a particle diameter greater than 10 xcexcm is undesirable in terms of the uniformity of the photosensitive layer.
Common dispersion techniques employed in the manufacture of ink, toner, and the like can be used to disperse the pigment. Examples of dispersion devices include ultrasonic dispersers, sand mills, attritors, pearl mills, super mills, ball mills, impellers, disperses, KD mills, colloid mills, dynatrons, three-roll mills, and pressure kneaders. Details are available in Saishin Ganryo Oyo Gijutsu [Recent Pigment Applications and Techniques] (published by CMC (1986 ed.)).
Commercially available and well-known dyes given in documents such as Senryo Binran [Dye Manual] (ed. Yuki Gosei Kagaku Kyokai (1970 ed.)) can be used. Specific examples include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, squarylium dyes, and metal thiolate complexes.
Of these pigments and dyes, those that absorb infrared rays and near infrared rays are preferred because they are suitable for use with lasers emitting infrared or near infrared rays.
Carbon black is preferably used as the pigment absorbing such infrared or near infrared rays. Examples of dyes absorbing infrared and near infrared rays include the cyanine dyes given in Japanese Patent Application Laid-Open (JP-A) Nos.58-125246, 59-84356, 59-202829, and 60-78787, the methine dyes given in Japanese Patent Application Laid-Open (JP-A) Nos.58-173696, 58-181690, and 58-194595, the naphthoquinone dyes given in Japanese Patent Application Laid-Open (JP-A) Nos.58-112793, 58-224793, 59-48187, 59-73996, and 60-52940, and 60-63744, the squarylium dyes given in Japanese Patent Application Laid-Open (JP-A) No. 58-112792, and the cyanine dyes given in UK Patent 434,875.
The infrared absorbing sensitizer noted in U.S. Pat. No. 5,156,938 is also suitable for use as a dye. Particularly desirable for use are the substituted arylbenzo(thio)pyrylium salts in U.S. Pat. No. 3,881,924, the trimethine thiapyrylium salts in Japanese Patent Application Laid-Open (JP-A) No.57-142645 (U.S. Pat. No. 4,327,169), the pyrylium compounds in Japanese Patent Application Laid-Open (JP-A) Nos.58-181051, 58-220143, 59-41363, 59-84248, 59-84249, 59-146063, and 59-146061, the cyanine dyes in Japanese Patent Application Laid-Open (JP-A) No.59-216146, the pentamethine thiopyrylium salts and the like in U.S. Pat. No. 4,283,475 or the pyrylium compounds Epolight III-178, III-130, and III-125 disclosed in Japanese Examined Patent Applications (Kokoku) 5-13514 and 5-19702.
Other particularly desirable examples of dyes include the infrared absorbing dyes given under Formulas I and II in U.S. Pat. No. 4,756,993.
The dyes and pigments are preferably added in an amount of between 0.01 and 50 wt %, and more preferably between 0.1 and 10 wt %, relative to the total solids of the photosensitive composition. Dyes are even more preferably added in an amount of between 0.5 and 10 wt %, while pigments are even more preferably added in an amount of between 1.0 and 10 wt %, to the photosensitive composition. Adding less than 0.01 wt % pigment or dye results in lower sensitivity, whereas adding more than 50 wt % will stain the areas with no images during printing.
The dye or pigment may be added to the same layer as the other components, or it may be added to a separate layer. Infrared or near infrared absorbing dyes or pigments are preferred among the above. The dyes and pigments may be used in combinations of two or more.
Other Components
Various additives can be added to the positive photosensitive composition of the present invention. For example, onium salts, aromatic sulfone compounds, aromatic sulfonic acid ester compounds and the like have action as thermally decomposing materials, and can thus be added to improve the dissolution inhibition properties of the image areas in the developer.
Examples of onium salts include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, and arsonium salts. Examples of onium salts suitable for use in the present invention include the diazonium salts in S. I. Schlesinger, Photogr. Sci. Eng., 18, 387 (1974), T. S. Bal et al, Polymer, 21, 423 (1980), and Japanese Patent Application Laid-Open (JP-A) No.5-158230, the ammonium salts in U.S. Pat. Nos. 4,069,055 and 4,069,056, and Japanese Patent Application Laid-Open (JP-A) No.3-140140, the phosphonium salts in D. C. Necker et al, Macromolecules, 17, 2468 (1984), C. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo, Oct (1988), and U.S. Pat. Nos. 4,069,055 and 4,069,056, the iodonium salts in J. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. and Eng. News, Nov. 28, p. 31 (1988), European Patent 104,143, U.S. Pat. Nos. 339,049 and 410,201, and Japanese Patent Application Laid-Open (JP-A) Nos. 2-150848 and 2-296514, sulfonium salts in J. V. Crivello et al, Polymer J., 17, 73 (1985), J. V. Crivello et al, J. Org. Chem., 43, 3055 (1978), W. R. Watt et. al, J. Polymer Sci., Polymer Chem. Ed., 22, 1789 (1984), J. V. Crivello et al, Polymer Bull., 14, 279 (1985), J. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. V. Crivello et al, J. Polymer Sci., Polymer Chem. Ed., 17, 2877 (1979), European Patents 370,693, 233, 567, 297,443, and 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114, 410,201, 339,049, 4,760,013, 4,734,444, and 2,833,827, and German Patents 2,904,626, 3,604,580, and 3,604,581, the selenonium salts in J. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), and J. V. Crivello et al. J. Polymer Sci., Polymer chem. Ed., 17, 1047 (1979), and the arsonium salts in C. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo, October (1988).
Examples of counterions for the aforementioned onium salts include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesufonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and para-toluenesulfonic acid.
Particularly preferred among these are hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, and 2,5-dimethylbenzenesufonic acid.
The onium salts are preferably added in an amount of between 1 and 50 wt %, more preferably between 5 and 30 wt %, and even more preferably between 10 and 30 wt %.
Dyes having substantial absorption in the visible light range can be used as colorants for images. Liposoluble dyes and basic dyes are examples of favorable dyes.
Specific examples include Direct Yellow #101, Oil Yellow #103, Oil Pink #312, Oil Green BG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, Oil Black T-505 (by Orient Kagaku Kogyo), Victoria Pure Blue, crystal violet (CI 42555), methyl violet (CI 42535), ethyl violet, rhodamine B (CI 145170 B), malachite green (CI 42000), methylene blue (CI 52015), Eisen Spiron Blue C-RH (by Hodogaya Chemical), and the like, as well as the dyes given in Japanese Patent Application Laid-Open (JP-A) No.62-293247.
Such dyes are preferably added to distinguish between areas where images are and are not formed after imaging. The amount to add is preferably 0.01 to 10 wt % relative to the total solids of the photosensitive composition.
Cyclic acid anhydrides, phenols, and organic acids can be added to further improve sensitivity. Examples of cyclic acid anhydrides include those given in U.S. Pat. No. 4,115,128, such as phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endoxy-xcex944-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, xcex1-phenylmaleic acid anhydride, succinic anhydride, and pyromellitic anhydride.
Examples of phenols include bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4xe2x80x2-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4xe2x80x2,4xe2x80x3-tridydroxytriphenylmethane, and 4,4xe2x80x2,3xe2x80x3,4xe2x80x3-tetrahydroxy-3,5,3xe2x80x2, 5xe2x80x2-tetramethyltriphenylmethane.
Examples of organic acids include those given in Japanese Patent Application Laid-Open (JP-A)Nos.60-88942 and 2-96755, such as sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids. Specific examples include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluylic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid.
The proportion of the aforementioned cyclic acid anhydrides, phenols, and organic acids in the printing plate material is preferably between 0.05 and 20 wt %, more preferably between 0.1 and 15 wt %, and even more preferably between 0.1 and 10 wt %.
Nonionic surfactants such as those given in Japanese Patent Application Laid-Open (JP-A) Nos.62-251740 and 3-208514 and amphoteric surfactants such as those given in Japanese Patent Application Laid-Open (JP-A) Nos.59-121044 and 4-13149 can also be added to the photosensitive composition of the present invention in order to improve treatment stability for developing conditions.
Specific examples of nonionic surfactants include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, monoglyceride stearate, and polyoxyethylene nonylphenyl ether. Examples of amphoteric surfactants include alkyl di(aminoethyl) glycine, alkylpolyaminoethyl glycine hydrochloride, 2-alkyl -N-carboxyethyl-N-hydroxyethylimidazolinium betaine, N-tetradecyl-N,N-betaine types (such as Amorgen K, trademark by Dai""ichi Kogyo).
The proportion of the aforementioned nonionic surfactants and amphoteric surfactants in the photosensitive composition is preferably between 0.05 and 15 wt %, and more preferably between 0.1 and 5 wt %.
Pigments or dyes serving as image colorants or print-out agents for obtaining visible images immediately after heating during exposure can be added to the positive photosensitive composition of the present invention.
Examples of typical print-out agents include combinations of compounds that release acid upon being heated during exposure (acid-releasing agents) and organic dyes capable for forming salts. Specific examples include combinations of o-naphthoquinonediazide-4-sulfonic acid halogenides and salt-forming organic dyes such as those given in Japanese Patent Application Laid-Open (JP-A) Nos.50-36209 and 53-8128, and combinations of trihalomethyl compounds and salt-forming organic dyes such as those given in Japanese Patent Application Laid-Open (JP-A) Nos. 53-36223, 54-74728, 60-3626, 61-143748, 61-151644, and 63-58440. Examples of such trihalomethyl compounds include oxazole compounds and triazine compounds, both of which provide excellent stability over time and distinct printed images.
Epoxy compounds, vinyl ether compounds, the phenol compounds with hydroxymethyl groups or alkoxymethyl groups in Japanese Patent Application 7-18120, and the cross-linked compounds having action in inhibiting alkali dissolution in Japanese Patent Application 9-328937 are preferably added for the sake of storage stability.
Plasticizers can also be added to the positive photosensitive composition of the present invention as needed to make the coated film more flexible and the like. Preferred examples include butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, and acrylic acid or methacrylic acid oligomers and polymers.
Surfactants such as the fluorine surfactants in Japanese Patent Application Laid-Open (JP-A) No.62-170950 can be added to the positive photosensitive composition of the present invention to improve the coating properties. They are added in an amount of between 0.01 and 1 wt %, and preferably between 0.05 and 0.5 wt %, of the total photosensitive composition.
The positive photosensitive composition of the present invention can be produced by the following common methods for producing photosensitive compositions.
Photosensitive compositions are usually produced by dissolving the aforementioned components in a solvent and then spreading the resulting solution on a suitable support. Examples of solvents used in this case include, but are not limited to, ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N,N-dimethyl acetamide, N,N-dimethyl formamide, tetramethyl urea, N-methyl pyrrolidone, dimethyl sulfoxide, sulfolane, xcex3-butyrolactone, toluene, and water. Such solvents can be used alone or in combination. The concentration of the above components in the solvent (total solids including additives) is preferably between 1 and 50 wt %. The coated amount (solids) on the support after drying will vary, depending on the application, but in general is preferably between 0.5 and 5.0 g/m2 when used for photosensitive lithography.
Various coating methods can be employed, such as bar coater coating, rotary coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating. Although the apparent sensitivity increases as the coated amount decreases, the coating properties of the photosensitive film also decrease. The coated layer is the photosensitive layer of the photosensitive composition.
The support is a dimensionally stable material in the form of a sheet, such as paper, paper laminated with plastic (such as polyethylene, polypropylene, and polystyrene), metal sheets (such as aluminum, zinc, and copper), plastic films (such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, and polyvinyl acetal), and paper or plastic films with metals such as the above laminated or deposited thereon.
Polyester films or aluminum sheets are preferred as the support used in the present invention. of these, relatively inexpensive aluminum sheets with good dimensional stability are especially preferred. Suitable aluminum sheets are pure aluminum sheets, alloy sheets comprising aluminum as the main component and minute amounts of other elements, as well as plastic films with aluminum laminated or deposited thereon. Examples of different elements which can be incorporated in aluminum alloys include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of such different elements in alloys should be, at most, no more than 10 wt %. Although pure aluminum is especially desirable in the present invention, trace amounts of other elements may be included since it is technically difficult, in terms of refining, to produce entirely pure aluminum. The composition of aluminum sheets suitable for the present invention is not specified. Aluminum sheets of conventional well-known materials are suitable for use.
The aluminum sheets used in the present invention are about 0.1 to 0.6 mm thick, preferably 0.15 to 0.4 mm thick, and even more preferably 0.2 to 0.3 mm thick.
Although aluminum sheets may undergo surface roughening, the surface can first be degreased with a surfactant, organic solvent, alkaline aqueous solution, or the like to remove rolling oil from the surface, if desired, before surface roughening.
Various methods can be used for surface roughening on aluminum sheets. Examples include mechanical roughening methods, electrochemical surface dissolving roughening methods, and chemically selective surface dissolving methods. Examples of mechanical methods which can be used include well known methods such as ball polishing methods, brush polishing methods, blast polishing methods, and buff polishing methods. Electrochemical methods of roughening include methods carried out with the use of AC or DC in hydrochloric acid or nitric acid electrolytic solution. Methods combining these two, such as that disclosed in Japanese Patent Application Laid-Open (JP-A) No.54-63902, can also be used.
Aluminum sheets which have undergone such surface roughening treatment may undergo alkali etching treatment and neutralization treatment as needed, and then anodic oxidation treatment to improve surface water retention or friction resistance as desired. various electrolytes for forming porous oxidation films can be used as the electrolyte in the anodic oxidation treatment of the aluminum sheets. Sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or mixtures thereof are commonly used. The concentration of the electrolyte can be determined as needed depending on the type of electrolyte.
The conditions of anodic oxidation vary according to the electrolyte that is used and thus cannot be specified as a matter of absolute principle, but the electrolyte concentration is generally 1 to 80 wt % solution, the temperature of 5 to 70xc2x0 C., the current density is 5 to 60 A/dm2, the voltage is 1 to 100 V, and the electrolysis time is 10 seconds to 5 minutes. An anodic oxidation film of less than 1.0 g/m2 will result in unsatisfactory print durability and tends to result in what is referred to as damage stains, where damage to the parts of the photosensitive composition in the areas where no images are formed can result in ink adhering to the damaged portions during printing.
After the anodic oxidation treatment, the surface of the aluminum may be treated as needed to render it hydrophilic. Examples of such hydrophilicization treatments which may be used in the present invention include the alkali metal silicate (such as sodium silicate aqueous solution) methods given in U.S. Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. In these methods, the support may be dipped in a sodium silicate aqueous solution or electrolytically treated. The methods of treatment with potassium fluorozirconate given in Japanese Examined Patent Application (Kokoku) 36-22063 or polyvinylphosphonic acid in U.S. Pat. Nos. 3,276,868, 4,153,461, or 4,689,272 may also be used.
An undercoat layer can be provided as needed between the support and the photosensitive layer. Various organic compounds may be used as components in the undercoat layer, such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid and similar amino group-containing phosphonic acids, optionally substituent-bearing phenylphosphonic acids, naphthylphosphonic acid, alkylphosphonic acids, griseophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid or similar organic phosphonic acids, optionally substituent-bearing phenylphosphoric acid, naphthylphoshoric acid, alkylphosphoric acids and griseophosphoric acid or similar organic phosphoric acids, optionally substituent-bearing phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid and griseophosphonic acid or similar organic phosphinic acids, glycine or xcex2-alanine and similar amino acids, and triethanolamine hydrochloride and similar hydroxy group-containing amine hydrochlorides. These may be used in combinations of two or more.
Organic undercoat layers can be provided in the following manner. The aforementioned organic compounds are dissolved in water or an organic solvent such as methanol, ethanol, or methyl ethyl ketone, or combinations thereof, and the resulting solution is applied on aluminum sheets and dried, or alternatively, the aforementioned organic compounds are dissolved in water or an organic solvent such as methanol, ethanol, or methyl ethyl ketone, or combinations thereof, the aluminum sheets are dipped in the resulting solution to allow the aforementioned compounds to adhere thereto, and the sheets are then washed with water or the like and dried, so as to provide an organic undercoat layer. Solution with a concentration of between 0.005 and 10 wt % of the aforementioned organic compounds can by applied by a variety of techniques in the aforementioned two methods. The solution concentration is between 0.01 and 20 wt %, and preferably between 0.05 and 5 wt %, in the latter method, the dipping temperature is between 20 and 90xc2x0 C., and preferably between 25 and 50xc2x0 C., while the dipping time is between 0.1 second and 20 minutes, and preferably between 2 seconds and 1 minute. The solution used therein can be prepared to a pH ranging between 1 and 12 with a basic substance such as ammonia, triethylamine, or potassium hydroxide, or an acidic substance such as hydrochloric acid or phosphoric acid. Yellow dyes can also be added to improve the tone reproducibility of the photosensitive composition.
The organic undercoat layer is applied in an amount of between 20 and 200 mg/m2 and preferably between 5 and 100durability. The same is true with more than 200 mg/m2.
The photosensitive composition that has been prepared is ordinarily exposed and developed to produce images. Examples of active light ray sources used during exposure include mercury lamps, metal halide lamps, xenon lamps, chemical lamps, and carbon arc lamps. Examples of radiation rays include electron beams, X-rays, ion beams, and far infrared rays. Other examples which can also be used include g rays, i rays, deep-UV light, and high density energy beams (laser beams). Examples of laser beams include helium-neon lasers, argon lasers, krypton lasers, helium-cadmium lasers, KrF excimer lasers, solid state lasers, and semiconductor lasers. In the present invention, light sources with an emission wavelength from the near infrared to infrared regions are preferred. Solid state lasers and semiconductor lasers are particularly preferred.
Conventionally known alkaline aqueous solutions can be used as the developer and replenisher. Examples include sodium silicate, potassium silicate, tribasic sodium phosphate, tribasic potassium phosphate, tribasic ammonium phosphate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and similar inorganic alkali salts. Other examples include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, ethyleneimine, ethylenediamine, pyridine and similar organic alkali agents.
Such alkali agents can be used alone or in combinations of two or more.
Particularly desirable developers among such alkali agents include aqueous solution of silicates such as sodium silicate and potassium silicate because they allow the development properties to be adjusted depending on the concentration and the ratio between the alkali metal oxide M2O (M represents an alkali metal) and the silicon oxide SiO2 serving as a component in the silicate. Alkali metal silicates such as those given in Japanese Patent Application Laid-Open (JP-A) Nos.54-62004 and 57-7427 are effective.
When automatic developing machines are used, it is known that greater amounts of a photosensitive composition can be used without replacing the developer in the development tank for longer periods of time by adding an aqueous solution (replenisher) with higher alkaline strength than the developer to the developer. The use of this method of replenishment is preferred in the present invention as well. Various surfactants and organic solvents can be added to the developer and replenisher as needed to promote or inhibit development, and to improve the dispersion of the development gas and the ink affinity of the photosensitive composition for the areas without any images. Desirable surfactants include anionic, cationic, nonionic, and amphoteric surfactants. Hydroquinone, resorcin, sodium and potassium salts of inorganic acids such as sulfurous acid or hydrogensulfurous acid, and similar reducing agents, as well as organic carboxylic acids, defoaming agents, and hard water softeners can also be added as needed to the developer and replenisher.
The photosensitive composition which has been developed using the aforementioned developers and replenishers is post-treated with rinsing water, rinsing liquids containing surfactants and the like, or non-affinitizing liquids containing gum arabic or a starch derivative. Such treatments can be employed in various combinations as post-treatment when the photosensitive composition of the present invention is used for printing plates.
Automatic developing machines for printing plates are now being widely used to rationalize and standardize the manufacture of printing plates in the printing plate and printing industries. The photosensitive composition in the present invention can also be processed using automatic developing machines. Such automatic developing machines generally comprise a developer component and a post-treatment component, and comprise an apparatus for conveying the printing plates, various treatment solution tanks, and a spray apparatus wherein pumped processing solutions are sprayed through a spray nozzle as the exposed printing plates are horizontally conveyed during development. In a recent known method, the printing plates are processed by being dipped and transported by means of a guide roll or the like in the solution of processing tanks filled with processing solution. During such automatic processing, the process can be carried out as the processing solution is replenished with replenisher according to the amount of processing, operating time, and the like. So-called disposable processing can also be performed with essentially unused processing solution.
After image exposure, development, washing and/or rinsing and/or degumming, a device for removing the unneeded parts of an image can be used when there are unneeded image areas (such as film edge tracks of the source image film) on the photosensitive composition. A preferred example of such a removal method is the method in Japanese Examined Patent Application (Kokoku) 2-13293, where a removal solution is applied to the unneeded parts of the image, and is allowed to stand as such for a certain period of time, after which it is rinsed away. A method of development which is performed after active light rays from an optical fiber are directed onto the unneeded parts of the image, such as that in Japanese Patent Application Laid-Open (JP-A) No.59-174842, can also be used.
The photosensitive composition processed as described above can be coated with a non-affinitizing rubber as desired and then submitted to a printing process. A burning process may also be carried out to improve printing durability. When the photosensitive composition is subjected to a burning process, it should be treated with a conditioning solution such as that in Japanese Examined Patent Applications (Kokoku) 61-2518 and 55-28062 and Japanese Patent Application Laid-Open (JP-A) Nos.62-31859 and 61-159655. Examples of such methods include those in which the conditioning solution is applied with a sponge or absorbent cotton dipped in the conditioning solution onto the photosensitive composition, or the photosensitive composition is dipped in a vat filled with the conditioning solution, or the conditioning solution is applied with an automatic coater. Once applied, the amount of the solution should be evened out with a squeegee or a squeegee roller. The conditioning solution is generally applied in an amount of between 0.03 and 0.8 g/m2 (dry weight).
After the photosensitive composition with the conditioning solution applied has been dried, it may be heated to an elevated temperature using a burning processor (such as the BP-1300 burning processor by Fuji Photo Film) or the like. The heating temperature and time depends on the type of components forming the image but should generally range between 180 and 300xc2x0 C., and between 1 and 20 minutes.
The photosensitive composition having undergone such a burning process can then be treated as needed by conventional methods such as rinsing and degumming, but so-called non-affinitizing treatments such as degumming can be left out when a conditioning solution containing water-soluble polymer compounds or the like is used.
The photosensitive composition processed in this manner is incorporated in offset printing presses or the like for use in printing used paper or the like.